Water permeating underground is artificially recovered and reused so that the valuable water resource is effectively utilized mainly in a region with small rainfall. A conventional water collecting system includes a waterproof sheet or the like for recovering and storing rainwater falling or irrigation water supplied onto a ground surface of farmland or the like using a slanted water shield layer.
For example, Patent Literature 1 discloses a system including a water shield layer, for collecting and supplying water using the slanted water shield layer. Patent Literature 2 discloses providing a slanted bottom wall and a side wall that are made of a water shield material and limiting a water flow path so as to allow water to flow in slanted soil and improve water clarification. According to Patent Literature 1 and Patent Literature 2, the water shield layer is configured by a waterproof sheet or the like, which is broken due to vibration in civil engineering or ground change by an earthquake or the like, and cannot be self-repaired.
Meanwhile, Patent Literature 3 discloses a soil structure that includes a hydrophobic layer made of hydrophobic particles in soil located at a predetermined depth from a ground surface, in order to suppress the amount of evaporation in the soil and control the amount of water in the soil. The hydrophobic layer made of hydrophobic particles is provided in the soil structure so as to suppress evaporation in the soil. Patent Literature 4 discloses providing a water repellent layer made of water repellent particles in or below soil used for plant cultivation so as to suppress capillary rise of ground water and prevent salt damage.